1. Field of the Invention
The present invention concerns an ozone contact chamber utilizing the principle of laminar stratification of gas in a turbulent contact chamber. The resulting contact chamber is much shorter in height than the conventional tower contact chamber, and ensures a high degree of dissolution of ozone in water and, consequently, a high degree of oxidation of organic and metal impurities to a final oxidation state.
2. Description of the Related Art
It is known to introduce ozone into water to eliminate contaminants, in particular bacterial contaminants. Ozone has been used as a chemical treatment to oxidize organic matter, metals, bacteria, and viruses in the water being treated. Dissolved ozone also forms an oxide coating on the surface of submerged metals, preventing corrosion. An ozone molecule is a rapid oxidizer that will oxidize organic matter quickly. Oxidized organics and metals can gain electrons and assume a positive attraction for other negatively charged particles, causing them to amalgamate, forming larger clumps easily removed by a filter.
The ozonation process can be broken down into two steps: (1) production of ozone in the form of a gas, and (2) contacting water with the ozone gas for a time sufficient to achieve some degree of oxidation of organics and metals present in the water. No matter how the ozone is produced, ozonation is not effective unless the gas water interface is broken and the ozone is sufficiently dissolved within the water being treated. Thus, many attempts have been made to optimize ozone-water contact.
In conventional ozone contact chambers, the ozone gas is applied at the base of a tall column. The ozone-oxygen bubbles float to the surface slowly, their upward movement slowed by the downward counter flow of the water stream. In order to achieve a sufficient contact time for the ozone to dissolve in the water before the water and ozone pass from the mixing column, the counter-current flow mechanism is combined with a tall contact column. The column must be extremely tall and is difficult to install in ordinary sized plant equipment rooms. The concentration of dissolved ozone-oxygen is undesirably diluted in the larger vertical columns. While ozone-oxygen contact in mixing chambers is generally effective, there is a need for improved mixing in more compact sized mixing vessels.
Attempts to improve the contact particularly in conjunction with swimming pools are described in U.S. Pat. No. 4,640,783 (Kern) and U.S. Pat. No. 4,966,717 (Kern). However, these systems require much space or must be deployed inside the swimming pool itself. Further improvements are required.
Ozone generators designed specifically for use in treatment of water are also well known. However, upon closer inspection, it can be seen that each of these designs is associated with inherent disadvantages.
For example, U.S. Pat. No. 5,451,318 (Morehead) teaches a filtration system for water or other selected liquids that includes an ozone mixing station, a primary solids and gas separator and, if desired, a second vortex particle separator and filter system. The ozone mixing station includes a high efficiency ozone generator and a channel arrangement, such as a spiral tubular treatment coil, through which the ozone/liquid mixture passes to assure thorough mixing and provide time for effective treatment. In practice, it has been found that the amount of energy required to force water through a spiral tubular treatment coil, particularly in counter-current flow arrangement, results in a significant pressure drop between the water inlet and water outlet side of the coil. Further, there is room for improvement in the water-ozone contact.
U.S. Pat. No. 5,709,799 (Engelhard) simply teaches bubbling ozone through a short tank containing water to be treated and venting ozone as it reaches the top of the tank. This design produces little effective ozone-water contact.
U.S. Pat. No. 4,141,830 (Last) teaches an ozone/ultraviolet water purifier wherein ozone is generated in a tubular chamber from which it enters the bottom of a water column and flows upwards along with upwards flowing water. This design, in addition to being tall, is inefficient in that it does not even take advantage of a counter-current flow mechanism to amplify the effective ozone-water contact time.
U.S. Pat. No. 5,266,215 (Engelhard) and U.S. Pat. No. 5,540,848 (Engelhard) teach a compact but inefficient water purification unit, wherein an ozone generator may be incorporated to entrain ozone along with inflowing water. Since the ozone flows along with water rather than counter-current, and since the contact column is short, the ozone-water contact is not optimal.
U.S. Pat. No. 5,674,312 (Mazzei) teaches an apparatus and process for injecting high concentrations of a treatment gas into a liquid stream which is devoid of undissolved gas or a gas phase. The liquid stream is passed through a gas inducing injector to receive treatment gas, and then is passed through a centrifugal liquid/gas separator from which entrained gases and liquid with dissolved treatment gases are separately withdrawn. Although the conduit in which gas injection into the liquid stream occurs is indicated to have a length selected to provide enough residence time for the intended liquid/gas exchange to occur, contact time is relatively short, the gas travels along with the liquid and not in counter-current manner, and unused gas must be withdrawn, which evidences that the ozone-water contact is in need of improvement.
U.S. Pat. No. 4,123,800 (Mazzei) teaches an injector-mixer in which the contact chamber is extremely small, and in which the residency time is short.
There is thus a need for a device which optimizes ozone-water contact, which is compact and efficient, and which does not impede the flow of water.